1. Field of the Invention
The present invention relates to an apparatus for watching around a vehicle and more particularly to an apparatus for allowing a driver within a vehicle such as an automobile to observe scenes and the like on both left and right sides of the vehicle.
The present invention also relates to an apparatus for watching around a vehicle by picking up an image in a dead angle area around the vehicle in order to display the image within the vehicle.
2. Description of the Related Art
When an automobile approaches an intersection, it will be necessary for a driver to ensure safety on left and right sides. At any intersection offering poor lateral visibility, however, the driver has had to cause the vehicle to enter the intersection zone a little bit so as to make sure of safety on left and right sides. At that time, the driver needs to pay careful attention to moving the vehicle into the intersection zone and also making sure of safety by directly watching scenes on both the left and right sides after entering the intersection zone, which has mentally given the driver a burden.
In order to reduce the aforementioned burden, there has recently been proposed a visual observation apparatus in such a system as to mount an image pick-up unit on the hood, front grill and bumper of an automobile and by using the image pick-up unit to take in scenes on left and right sides of the vehicle so that images about left and right sides thereof may simultaneously be displayed on a display unit provided within the vehicle.
Moreover, there has also appeared an apparatus for displaying a mask image that is divided into left and right images in order to improve the discriminability between the left and right images in a case where the left and right images are simultaneously displayed on the display unit.
The masking systems disclosed in JP-A-10-104765 have adopted as what marks off the left image from the right one by compounding each of the left and right images and a window type mask using a trimming image and as what limits a range of pick-up visual fields corresponding to the mask position. The mask area of a mask image has heretofore been displayed in a single color such as black.
In such a case that the mask area is displayed in a dark color of black or the like, the drawback is poor visibility in that though the boundary between the left and right images and the mask image is distinctly recognized because the left and right images are brightly displayed in the daytime time zone, a dark portion (black portion) of each of the left and right images becomes greater in a time zone where the outside of the vehicle is dark and this makes it difficult to clearly recognize the boundary between the left and right images and the mask image.
In addition, it will be unnecessary to display both the left and right sides by means of any display device during normal cruising other than, for example, entering any intersection providing poor lateral visibility. In order to reduce power consumption, there has also been proposed an apparatus for stopping the supply of power to power supply circuits and image output circuits of the image pick-up unit such as CCD cameras whenever the vehicle travel speed, or the vehicle speed exceeds a predetermined level.
In the conventional apparatus for watching around a vehicle, however, electric power is supplied simultaneously to the power supply switch of an image pick-up means such as a CCD camera and an image output circuit in cases where the vehicle is traveling at a predetermined speed or lower, which results in taking a certain time to start the power supply within the image pick-up unit such as a CCD camera and to initialize an internal microcomputer and an LSI; namely, taking as long as about one second. During this time, the operation of an image signal tends to become unstable and as a normal signal is not output, a noise image is displayed in a display unit. The shortcoming is that display quality is deteriorated.
By the way, an apparatus for watching around a vehicle of the sort mentioned above is used to watch around a vehicle by causing images around the vehicle to be displayed during the travel of the vehicle on narrow streets offering poor visibility. However, the display of such images becomes unnecessary during the travel of the vehicle offering unobstructed view. Therefore, it is needed to switch the on and off states of displaying images around the vehicle by the apparatus for watching around a vehicle.
Consequently, an operating switch for switching the on and off states of the display of images around a vehicle is provided in the prior art to such an apparatus for watching around a vehicle so that a driver may operate the switch (first prior art).
Further, information on spots with poor visibility is included in car navigation maps to allow an apparatus for watching around a vehicle to decide whether the display of images around a vehicle will be needed on the basis of positional information indicating the present position of the vehicle by means of the information on spots with poor visibility, GPS and the like, whereby switching the on and off states of image display can be conducted automatically (second prior art).
However, the first prior art develops a problem arising from troublesome operation of switching the on and off states of the display of images around the vehicle.
With respect to the second prior art, though switching the on and off states of the display of images around the vehicle is automatically conducted, information on spots with poor visibility is needed to be included in the map information. Moreover, the problem is that an expensive system is also needed to detect the present position of the vehicle with precision in order to precisely decide whether or not the display of peripheral images will be needed, which results in increasing equipment cost.
It is therefore an object of the present invention to provide an apparatus for watching around a vehicle so designed to improve the visibility of the boundary between picked-up images and a mask image.
Another object of the present invention is to provide an apparatus for watching around a vehicle by effectively preventing a noise image from being displayed on a display unit in order to improve display quality at the same time.
Still another object of the present invention is to provide a low-cost apparatus for watching around a vehicle capable of switching the on and off states of the display of images around a vehicle precisely and automatically depending on the visibility around the vehicle.
To technically solve the foregoing problems, there is provided an apparatus for watching around a vehicle according to the invention using an image pick-up unit to be mounted on the exterior of the vehicle to pick up images of the surroundings of the vehicle so that the images thus picked up thereby together with a mask image which is superimposed on the picked-up images can be displayed on a display unit provided within the vehicle, which is characterized in that the apparatus for watching around the vehicle includes a light-to-dark decision unit for deciding the lightness outside the vehicle; the display color of the mask image is switchable from one to another; and the display color of the mask image is set switchable from one to another according to a light-to-dark decision signal from the light-to-dark decision unit.
The apparatus for watching around a vehicle functions as what picks up both left and right surroundings of the vehicle, causing the left and right images thus picked up to be displayed on the display unit separately or simultaneously, and also displaying the mask image in a manner specifying the left or right image.
In the apparatus for watching around a vehicle, a plurality of colors including light and dark colors are provided as the display color of the mask image, and the display color of the mask image may be switched to the dark color when the luminous intensity outside the vehicle is decided to be high through the light-to-dark decision signal, and to the light color when the luminous intensity outside the vehicle is decided to be low therethrough.
In the apparatus for watching around a vehicle, the light-to-dark decision unit has a lamp lighting circuit mounted on the vehicle, and the light-to-dark decision signal includes a light-on and a light-off signal of the lamp lighting circuit, thereby to switch the display colors of the mask image when the luminous intensity outside the vehicle is decided to be high by the light-off signal or when the luminous intensity outside the vehicle is decided to be low by the light-on signal.
A means of technically solving the foregoing problems by an apparatus for watching around a vehicle using an image pick-up element to be mounted in the vehicle to pick up images on both the left and right sides of the surroundings of the vehicle and displaying the left and right images thus picked up on a display unit provided within the vehicle via an image control unit, wherein the image control unit may comprise an image pick-up element power switch for turning on and off the operating circuit of the image pick-up element, an image output signal switch for turning on and off an image output circuit for subjecting an image signal picked up by the image pick-up element to a conversion process and supplying the converted image signal, and a switch control portion having the upper threshold speed of vehicle speed for turning on and off the image pick-up element power switch and a lower threshold speed of the vehicle speed for turning on and off the image output signal switch and wherein the image pick-up element power switch may be turned on by the switch control portion when it is detected that the vehicle speed reaches the upper threshold speed during the time of speed reduction and the image output signal switch is turned on by the switch control portion when it is detected that the vehicle speed reaches the lower threshold speed during the time of speed reduction.
An apparatus for watching around a vehicle may be such that the image pick-up element power switch as well as the image output signal switch is turned off by the switch control portion when it is detected that the vehicle speed reaches the lower threshold speed.
An apparatus for watching around a vehicle may be such that the image control unit includes a display unit power switch for turning on and off the operating circuit of the display unit, wherein the display unit power switch and the image pick-up element power switch are turned on and off in synchronization with each other by the switch control portion.
In order to technically accomplish the object above, an apparatus for watching around a vehicle by picking up images of dead angle areas around the vehicle to display the images within the vehicle, comprises: an image pick-up unit for picking up images of dead angle areas around the vehicle; a display unit for displaying the images picked up by the image pick-up unit; a distance measuring unit for detecting the distance between the vehicle and an obstacle so positioned as to obstruct the view of a driver on at least one side out of both sides of the vehicle during the travel of the vehicle; and a controller for deciding whether or not the display of the image on the display unit will be needed on the basis of the distance detected by the distance measuring unit and controlling the display unit over switching the on and off states of display according to the decision made thereby.
Preferably, the apparatus for watching around a vehicle is such that the distance measuring unit detects the distance between the vehicle and each of the obstacles positioned on both the left and right sides of the vehicle during the travel of the vehicle; and the controller detects a space between the left- and right-hand obstacles on the basis of the distance between the vehicle and each of the left- and right-hand obstacles detected by the distance measuring unit, regards the space as width of a road on which the vehicle is traveling, decides whether or not the display of the image on the display unit will be needed on the basis of the value of the width thereof, and controls the display unit over switching the on and off states of display according to the decision made thereby.
Preferably, the apparatus for watching around a vehicle further comprises a travel-condition detector for accepting at least one vehicle signal for making reduced vehicle speed detectable out of vehicle signals indicating travel conditions which are output from a plurality of vehicle portions, and detecting the reduced vehicle speed according to the one vehicle signal, wherein the controller decides whether or not the display of the image on the display unit will be needed on the basis of the width of the road detected by the distance measuring unit and the result detected by the travel-condition detector, and controls the display unit over switching the on and off states of display according to the decision made thereby.
Preferably, the apparatus for watching around a vehicle further comprises a travel-condition detector for detecting vehicle speed by accepting a vehicle signal indicating vehicle speed, wherein the controller decides that the display of the image by the display unit will be needed only in case where the width of the road detected by the distance measuring unit is equal to a predetermined reference distance or less and where the vehicle speed detected by the travel-condition detector is a predetermined reference speed or lower, and causes the image to be displayed on the display unit.
Preferably, the apparatus for watching around a vehicle is such that the image pick-up unit is installed in the front end portion of the vehicle and used to pick up images in left and right directions in front of the vehicle.